Base transit time of submicron bipolar transistors including nonuniform base doping profile and high current effects

An analytical /spl tau//sub B/ model of submicron bipolar transistors valid for arbitrary levels of injection and Gaussian base doping profile is presented in this paper. For the devices considered, our calculations show that the conventional model (considers uniform base doping profile and no base pushout) overestimates /spl tau//sub B/ by a factor of about 2.5 at low injection and underestimates /spl tau//sub B/ by a factor of about 1.5 at high injection. Besides, /spl tau//sub EC/ calculated from present model compares favorably with experimental data measured from a 0. 12 /spl mu/m base width BJT.